Answer:
A.
![f(x)=6x+9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/438cuaymd811xs382fmnao65816ghwua52.png)
Explanation:
We have been given an equation
. We are asked to write our given equation in function notation with x as the independent variable.
First of all, we will convert our given equation in slope-intercept form by separating y on one side of equation.
![y-6x-9=0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xvaln414ncxq6yhnyetiy1y26nnic2ptlo.png)
![y-6x+6x-9=0+6x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/k5ky0mqm3j16tw0detuz11akloibzxahr5.png)
![y-9=6x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xfjhu7f8rdxjhvo8y0kj9xyui8igo57tdi.png)
![y-9+9=6x+9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vyowf4ykr2suj93sh30lyfxlca70ngcgzl.png)
![y=6x+9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/lehi53bm7uvl9zyutzuig91h524xvpc5lj.png)
Now, we will replace
with
.
![f(x)=6x+9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/438cuaymd811xs382fmnao65816ghwua52.png)
Therefore, our required function would be
and option A is the correct choice.